bleaaaaaaaah.
The way FF14 is set up is simultaneously it's biggest strength and biggest flaw. You can't just jump in and start playing, you have to chew your way through all of A Realm Reborn, Heavensward, and Stormblood before you get to start on Shadowbringers. You can buy story skips but that would destroy what made Shadowbringers so memorable, like if Infinity War came out without 10 years of building up the MCU first but beyond even that because they plainly didn't have all this planned out at the start but Ishikawa takes all these disparate threads from the previous three expansions and weaves them together into a fantastic overarching story.
You don't need a static group for anything in FF14 except the highest difficulty optional content. FF11 was more in the old school Everquest style of MMOs wasn't it? FF14 is very much a contemporary design with a story (main scenario quests) that will provide more than enough xp to keep you from having to grind to level your primary job, and there's an xp bonus when you're still working your way through old content so you can keep two or even three jobs leveled at once.
but god damn ARR is a fucking slog, even with all the work they've done over the years to slim it down and speed it up. A Realm Reborn is like the first two seasons of Deep Space Nine.